The present invention relates to apparatus for extracting samples of liquid from flow lines or vessels.
Certain manufacturing operations require that the immediate or overall composition of a liquid product flowing through a pipe or contained within a vessel or tank be monitored. Such monitoring may be accomplished using a sampling apparatus to take samples of product from a main body of the product. Where a composite sample of the product is required, the sampler is operated periodically to withdraw a series of small, measured amounts of the product at a sampling point, which individual samples are collected and mixed to form a composite sample representative of the total volume of product. If the immediate composition of the product is to be determined, individual samples are not collected and mixed, but are analyzed separately.
Four exemplary types of sampling apparatus of a type contemplated by the prior art are disclosed in U.S. Pat. Nos. 4,147,062, 4,262,553, 4,475,410 and 4,744,255, issued to Ben E. Jaeger, the present inventor, and the teachings of all of which are incorporated herein by reference. Sampling apparatus of the type disclosed in said patents is attached to an access line to a pipe or vessel containing liquid product. The samplers have a plunger that can be extended through the access line to project a sample receiving recess in the plunger into the main body of product in the pipe or vessel for receiving a product sample in the recess. The plunger is then retracted to move and deliver the product sample in the recess to a collection point in the sampler.
A disadvantage of the samplers of said patents is that they are always directly coupled through the access line with the interior of the pipe or vessel. The samplers therefore cannot be disconnected from the access line for replacement, repair or maintenance without first interrupting the presence of product in the pipe or vessel in the vicinity of the access line, since otherwise removal of the sampler from the access line would result in an uncontrolled outflow of liquid product through the access line.
U.S. Pat. No. 4,628,732, issued Dec. 16, 1986 and the teachings of which are incorporated herein by reference, teaches a connecting device for coupling a passive measuring instrument to a process having a parameter to be measured. The parameter may comprise temperature, density, pH value, consistency or some other characteristic of the process. The connecting device has a valve member through which a bore extends, and the valve member is movable between positions placing the bore into and taking the bore out of communication with the process. The measuring instrument connects to and is received within the valve bore. When the valve is positioned to place the bore into communication with the process, the measuring instrument can be extended through the bore and into the process to measure the parameter of the process. To replace or repair the measuring instrument, it is retracted from the process and the valve is moved to the position taking its bore out of communication with the process. The measuring instrument can then be disconnected from the valve member and removed from the valve bore without escape of process through and out of the bore. However, while the apparatus of said U.S. Pat. No. 4,628,732 permits a parameter of a process to be measured, it does not accommodate removal of a sample of the process.
U.S. Pat. No. 5,905,213, issued May 18, 1999 to the present inventor and the teachings of which are incorporated herein by reference, overcomes the aforementioned disadvantages of prior art samplers. According to this patent, principal components of a sampler for a liquid product can be disconnected from communication with an access line to the product without resulting in an uncontrolled outflow of liquid product through the access line. A forward end of a sampler housing is coupled to a movable valve for movement with the valve, and the housing and valve have axially aligned bores. Movement of the valve places the forward end of its bore into and out of communication with an opening in the access line leading to the interior of a vessel containing the liquid product. A plunger in the housing bore has a sample receiving recess intermediate its ends, and with the forward end of the valve bore placed into communication with the interior of the vessel, the plunger is reciprocated forward in the housing and valve bores to project the recess into the vessel to receive a product sample therein. The plunger is then reciprocated rearward to retract the product sample containing recess from the vessel and through the valve and housing bores to a sample collection point in the housing. Should the sampler require repair or replacement, the valve is moved to place the forward end of the valve bore out of communication with the vessel interior, whereupon the sampler housing can be disconnected from the valve without outflow of liquid product from the vessel through the valve bore. A disadvantage of the arrangement is that the entirety of the sampler moves conjointly with movement of the valve between its open and closed positions, so a relatively large unobstructed area must be provided around the sampler to accommodate such movement, which limits freedom of location of the sampling apparatus. In addition, to accommodate mounting of the sampler housing on the valve, the valve must be relatively large to accommodate connection of the sampler housing to it, resulting in increased manufacturing costs.
An object of the present invention is to provide a liquid sampler that can be removed from connection with a pipe or vessel carrying a liquid product to be sampled, without disturbing the product in the pipe or vessel.
Another object is to provide such a sampler that includes a valve that can be opened to place principal components of the sampler into communication with product in the line to permit the sampler to obtain one or more discrete samples of the product from the line.
A further object is to provide such a sampler in which the valve can be closed to place principal components of the sampler out of communication with product in the line to permit the components to be removed for service, repair or replacement without disturbing the product in the line or resulting in an uncontrolled outflow of product from the line.
Yet another object is to provide such a sampler in which the valve, when placing the sampler principal components into communication with the product in the line, accommodates extension of a sampling recess in a sampler plunger through a bore in the valve and into the product for receiving in the recess a product sample of measured volume for removal to a remote sampling point.
In accordance with the present invention, a sampling apparatus comprises a sampler that is operable to obtain discrete samples of liquid from a body of liquid in a vessel, and a connecting device for coupling the sampler to the vessel at an aperture to the vessel. The sampler is attached to the connecting device, and the connecting device is operable between a first position placing the sampler into communication with the liquid in the vessel through the aperture, and a second position taking the liquid sampler out of communication with the aperture and the liquid in the vessel. When the connecting device is in the second position, the sampler can be detached from the connecting device for service or replacement without liquid escaping from the vessel through the connecting device. The sampler includes sampling means that is extended, when the connecting device is in the first position, through the connecting device and into the vessel through the aperture to obtain a sample of liquid from the vessel, and that is then retracted from the vessel through the aperture and the connecting device to carry the liquid sample to a sample collection point. So that only liquid samples reach the collection point, seal means are provided to maintain a liquid seal between the liquid in the vessel and the sample collection point while the connecting device is in the first position. The sampler remains stationary when the connecting device is operated between the first and second positions, so that additional space to accommodate movement of the sampler need not be provided around the sampler and connecting device when the same are coupled to the vessel.
In a contemplated embodiment, the sampler includes a plunger having a sample receiving recess, and means are provided for reciprocating the plunger. When the connecting device is moved to the first position, the reciprocating means extends the plunger and its recess through the connecting device and the aperture into the liquid in the vessel to receive in the recess a sample of liquid. The reciprocating means then retracts the plunger and its recess from the vessel and through the aperture and the connecting device to deliver the liquid sample in the recess to the sample collection point. The connecting device includes a valve member having a bore, and the valve member is movable between the first and second positions. The valve member bore extends between the sampler and the aperture to the vessel when the valve member is moved to the first position, for reciprocation of the sampler plunger and its recess through the bore. The valve member bore is out of communication with each of the sampler and the aperture when the valve member is moved to the second position, whereupon the sampler can then be removed from the connecting device without escape of liquid from the vessel through the connecting device.
The means for maintaining a seal between the vessel interior and the sample collection point includes seal means carried by the plunger on opposite sides of the plunger recess, and the connecting device has a shell. The connecting device valve member comprises a ball valve contained within the shell, and the valve member bore extends generally diametrically through the ball valve. Means are provided for rotating the ball valve in the shell between the first and second positions, and the connecting device includes seal means in the shell for maintaining a seal between the ball valve bore and each of the vessel aperture and the sampler when the ball valve is rotated to the second position. The sampler includes a body, the plunger is received and reciprocated in the body, and the sampler body is attached to the connecting device shell.
The means for reciprocating the sampler plunger may include motor means, such as pneumatic motor means, coupled to the sampler plunger and attached to the sampler body opposite from attachment of the sampler body to the connecting device shell. The sampler plunger and the ball valve bore are generally cylindrical and are in a substantially coaxial orientation when the ball valve is rotated to the first position, so that reciprocation of the plunger through the valve member bore is unobstructed. When the ball valve is rotated to the second position, the axes of the plunger and bore are generally perpendicular.
The sampler body has a bore in which the plunger is received, and the sampler body bore is in substantial axial alignment with the ball valve bore when the ball valve is rotated to the first position. The sample collection point is in the sampler body bore, and the plunger is retracted into the sampler body bore to move its recess and the liquid sample in the recess to the sample collection point. Means are provided in the sampler body at the sample collection point for receiving the liquid sample from the plunger recess. Also included is means for releasably locking the connecting device ball valve in each of the first and second positions.
The foregoing and other objects, advantages and features of the invention will become apparent upon a consideration of the following detailed description, when taken in conjunction with the accompanying drawings.